Xanthenone-1-acetic acid has been prepared previously (H. Nichino and K. Kurosawa, Bull. Soc. Chem. Jap., 1983, 56, 2847), and has been evaluated as an anti-inflammatory agent (M. Nakanishi, T. Oe, M. Tsuruda, H. Matsuo, S. Sukuragi, Y. Maruyama, Yakugaki Zasshi, 1976, 96, 99; Chem. Abstr. 1976, 84, 135515b). Xanthenone-2-acetic acid has also been reported previously (M. Henryk, Pol. J. Chem., 1980, 54, 2059) and has been evaluated as an anti-inflammatory agent (M. Nakanishi, T. Oe, Y. Maruyama, Ger. Offen. 2,015,265; Chem. Abstr. 74P, 13008m: M. Nakanishi, T. Oe, S. Kakuragi, Japan 73 26 767; Chem. Abstr. 78P, 159430x). Xanthenone-4-acetic acid has been prepared previously (H. Nishino and K. Kurosawa, Bull. Soc. Chem. Jap., 1983, 56, 2847), and has been evaluated as an anti-inflammatory agent (M. Nakanishi, T. Oe, M. Tsurada, H. Matsuo, S. Sakuragi, Y. Maruyama, Yakugaku Zasshi, 1976, 96, 99; Chem. Abstr. 1976, 84, 135515b; M. Nakanishi, T. Oe, Y. Manuyama, Japan 72 00 425; Chem. Abstr. 1972, 76P, 126784e).